Dosage-dispensing devices with dosage-dispensing units, which normally include a source container and a dosage-dispensing head, are used in particular in the dispensing of small dosage quantities of, for example, toxic substances with high precision into small target containers. Such target containers are often placed on a balance in order to weigh the substance delivered out of the dosage-dispensing device, so that the substance can subsequently be processed further in accordance with given instructions.
In U.S. Pat. No. 7,284,574 B2 a dosage-dispensing device is described in which a dosage-dispensing unit including a source container and a dosage-dispensing head can be inserted. The dosage-dispensing head contains a basic body which has an end surface and a coupling area for a source container. Further, at the end surface of the basic body, there is an outlet opening arranged which is connected to the coupling area. The outlet opening can be closed off with a rotary slider which is connected to the basic body with the freedom to swivel about the central longitudinal axis of the basic body, wherein said central longitudinal axis is arranged parallel to the end surface. At the end of the rotary slider that is accessible from the outside, there is a cross-slotted aperture-setting member arranged which serves to actuate the rotary slider through engagement with the end of a driving shaft that is shaped like a Phillips screw driver. By turning the rotary slider which is coupled with the driving shaft, the outlet opening can be set free to a variable degree of aperture, so that the dosage material moves through the outlet opening and flows into a target container. As the rotary slider, due to its design, will deflect the outflow path of the dosage material, the latter has to be channeled by a housing part below the outlet opening, in order to also allow the dosage material to be dispensed into target containers with a narrow filler opening.
The dosage-dispensing head of a dosage-dispensing device described in U.S. Pat. No. 7,614,429 B2 contains a basic body which has an end surface and a coupling area for a source container. Further, on one side surface of the basic body there is an outlet opening arranged which is connected to the coupling area. The outlet opening can be covered by a slider which is constrained on the basic body in guided linear sliding movement parallel to the side surface. The actuation of the slider occurs by way of a ring-shaped aperture-setting member to which the slider is mechanically connected. By vertically moving the aperture-setting member, the outlet opening can be set free to a variable degree of aperture, so that the dosage material moves out of the outlet opening. As the outlet opening is arranged on a side surface, the dosage material does not move out vertically and therefore has to be channeled into a target container by means of funnel which is solidly fastened to the dosage dispensing head. Furthermore, the length of the shutter tongue can lead to problems with the tightness of the outlet closure.
The dosage-dispensing devices disclosed in U.S. Pat. No. 7,284,574 B2 and in U.S. Pat. No. 7,614,429 B2 suffer from the drawback that below the slider or the rotary slider the dosage material is guided into the target container by housing parts on which the dosage material can get caught, whereby the accuracy of the results can be compromised. This aspect is especially critical in cases where highly toxic substances are to be measured out and if, for example during the exchange of a dosage-dispensing unit, the remaining particles break loose from the latter and contaminate the ambient work area or the person attending to the apparatus.
This is the reason why the arrangements proposed in the prior art, due to their design layout, are suitable only for dosage material with good free-flow properties, such as liquids, granulates or special powders with particles that are approximately spherical and have a smooth surface, so that as little as possible of the dosage material remains clinging to the equipment.
In addition, the apparatus disclosed in U.S. Pat. No. 7,614,429 B2 involves a complicated and expensive construction and lacks the desired compactness.
The arrangements disclosed in U.S. Pat. No. 7,284,574 B2 are likewise fraught with a similar problem. While the design for the dosage-dispensing head disclosed in FIGS. 2 to 7 of U.S. Pat. No. 7,284,574 B2 can be produced as a compact device at a favorable cost, the mechanical configuration of the dosage-dispensing unit requires a labor-intensive assembly of the drive mechanism, as the dosage-dispensing unit is inserted vertically into the seating socket of the drive mechanism and, in order to be coupled, has to be turned about its vertical lengthwise central axis into the correct position, so that the drive shaft and the rotary slider are aligned with each other. In order to allow the rotary slider to be coupled to the drive shaft after the dosage-dispensing unit has been seated and aligned, it is necessary to move the drive shaft of the drive mechanism in a horizontal direction relative to the rotary slider.
It is therefore the object of this invention to provide a compact, low-cost dosage-dispensing head which allows the dosage material to be delivered with precision in regard to channeling the flow into the filler opening of the target containers and meeting the target quantity, and with safety against contamination, and which is conducive to a simple and cost-effective drive mechanism.